黄骅坳陷港中地区古近系沙三段湖底扇沉积相特征  

Sedimentary Characteristics of Sublacustrine Fan of the Third Member of Shahejie Formation in Gangzhong Oilfield,Huanghua Depression

作　　者：杨有星[1,2] 金振奎[1,2] 

机构地区：[1]中国石油大学地球科学学院,北京102249 [2]中国石油大学油气资源与探测国家重点实验室,北京102249

出　　处：《现代地质》2012年第2期355-362,共8页Geoscience

基　　金：国家重点基础研究发展规划("973"计划)项目(2006CB202300)

摘　　要：在沉积学和层序地层学理论指导下,通过分析地震剖面响应特征、测井曲线组合形态和岩心沉积构造,结合区域地质背景特点、重矿物及砂岩岩屑成分平面分布特征,研究认为港中地区沙三段发育两期完整的湖底扇沉积,每期湖底扇自下向上表现为正旋回沉积序列,扇面积为30～50 km2。湖底扇可进一步划分为4种亚相和7种沉积微相类型,其中中扇是湖底扇的主体部分,面积为15～20 km2。沙三段湖底扇的砂体并不只是由重力流成因形成的,在沉积作用前期,主要受重力作用控制,但在沉积作用后期,受牵引流和重力流双重作用控制。湖底扇物源主要来自研究区西缘的港西凸起。砂体总体呈朵叶状分布,为多期砂体叠置,在朵叶内部,中扇辫状水道砂体的物性最好,砂体顶底常被深黑色的泥岩所包围,具备非常好的油气富集条件。在港中地区沙三段中油组末期、沙三段上油组末期存在区域性或局部侵蚀界面,容易形成地层不整合油气藏;沙三段两期湖底扇沉积面积大,辫状水道较发育,并受后期构造活动发生变化,水道砂体尖灭在暗色泥岩之中,容易形成砂岩透镜体和砂岩上倾尖灭岩性油气藏。Based on the theory of sedimentology and sequence stratigraphy,and by analysis of seismic response characteristics,well logs,core sedimentary structures,the regional geological conditions and distribution of heavy minerals,it is concluded that two complete sublacustrine fans developed in the third Member of Shahejie Formation of Gangzhong Oilfield,which cover 30 km2 to 50 km2 and each exhibit a positive cyclic sedimentary sequence.The sublacustrine fans mentioned above could be further divided into four sub-sedimentary facies and seven microfacies,of which the middle-fans are main parts with the coverage of 15 km2 to 20 km2.Turbidity could not be the only cause for the formation of sublacustrine fans.In the early phase of deposition,the fan is mainly influenced by gravity,but in the late one,by traction together with gravity.The provenances of sublacustrine fans mainly come from the uplift of Gangxi.Sandstone distribution takes the flower-shape with multi-sand stacks.Braided channel of the middle-fan with best physical properties and surrounded by mudstone,can provide an excellent space for hydrocarbon accumulation.There are two regional erosional interfaces for stratigraphic reservoirs at the ends of middle and upper oil groups,the third Member of Shahejie Formation.The sublacustrine fans with quite large area and braided channel developed on it,where the sandstone pinches out in the mudstone,is easy to form lens and wedge outs of sandstone lithologic reservoirs.

关 键 词：黄骅坳陷 港中地区 沙三段 湖底扇 

分 类 号：TE121.3[石油与天然气工程—油气勘探]